Methods and Materials for Western Red Cedar

The bleaching-oil treatment, which was applied by Northwest Coating Systems in Woodburn, Ore., was an approach that Schellhase had never seen employed. The timber was sent directly from its sources—primarily in Idaho—to the mill and then to the treating company, where the pieces were dried and coated. Once the materials arrived on site, Schellhase and his team followed “heavy timber industry standards” including the American Wood Council (AWC) guide, Heavy Timber Construction.⁵ While the techniques originated for use in industrial and storage structures, they are commonly used for schools, auditoriums, gymnasiums and other assembly buildings.

Integrated MEP Makes Sandy High Greener According to Interface Engineering, which provided a raft of mechanical, electrical and plumbing (MEP) and sustainability services for the Sandy High School project, a whole-building integrated design strategy led to the green building choices behind it, including the use of western red cedar. The school uses several nontraditional techniques for maximizing whole-building efficiency and reducing energy needs. One is a geoexchange system, which has underground water pipes buried below the new athletic field. These “allow access to the earth’s relatively constant temperature—50 degrees) for free heating and cooling,” according to Interface Engineering. In fact, the closed-loop system of pulling and rejecting heat, in addition to the heat recovery chiller, may meet all of Sandy high school’s HVAC demands throughout the year, given typical weather. The school also employs radiant heating and cooling slabs in areas such as the cafeteria, auditorium, library, and entrance lobby. Enhancing the schools indoor environmental quality (IEQ) is a displacement ventilation system in the classrooms and learning areas.The building management systems use CO2 measurements to operate a demand-controlled ventilation system, which further reduces HVAC and energy use. On the roof, a 40-panel solar thermal hot-water heating system also saves energy. A solar panel array totaling 144 kilowatts supplies free electricity, and may be expanded in the future. According to the architects and engineers, some of the energy-saving systems were offset by a $600,000 incentive from the Energy Trust of Oregon.

 

Time Frame also hired quality carpenters and craftsmen to cut and assemble the Sandy High School panels and boards—several hundred thousand feet of which now make up the building's beams. The decking and siding each required another 100,000 feet of timber. A minimal amount of bleaching-oil treatment was done on site, around cut-ins and where touch-up work was needed.

The building's laminated deck consists of three layers—two pine and one western red cedar—pressed and glued together. The roof overhangs were constructed as panels and lifted into place, which saved time and made installation safer and easier than building them in place. The use of western red cedar may not have added to the work of a project of this nature, but it required a demanding combination of specialized materials, treatments and architectural detailing that are unlike a typical lodge or residential structure. For those reasons it may have required more labor hours than a typical building of comparable size, Schellhase says, “But the result is a totally unique project,” and it brings to the fore new ideas for the extensive use of western red cedar. “It's not something you see a lot of,” he adds.

Yet the project design team expects to see more commercial and institutional applications of western red cedar. While in some cases using western red cedar may be more costly than some typical materials used in educational construction, such as concrete masonry units or cast-in-place concrete, Schellhase and Waters point out that conforming to the Sandy Style as the design-and-construction teams did would have been difficult with another material. And in the end, the western red cedar exterior is expected to last a long time, given DOWA-IBI's innovative design, which the American Institute of Architects recognized in August 2013 with an Educational Facility Design Excellence Award. In its press release, the AIA said the building, which is LEED Gold-certified, “sets very high standards in terms of materials, finishes and aesthetics.”

The high LEED certification demonstrates the range of benefits of using western red cedar. The WRCLA summarizes that cedar has the “lowest environmental impact when compared with other materials such as brick and fiber cement.” Both Waters and Schellhase are confident that the school's exterior, beams, and decking will last as long as the building's anticipated service life, and won't require refinishing any time soon.